LONDON, England (CNN) -- Five people got the lavish ride of a lifetime as the only passengers on a transatlantic flight, causing environmental groups to criticize the major carrier for leaving a wasteful carbon footprint.

American Airlines has faced criticism for a transatlantic flight carrying only five passengers.

Using about 68,000 liters (15,000 imperial gallons) -- or 13,000 liters per passenger -- of jet fuel for the nine-hour trip from Chicago to London, American Airlines is being accused of unnecessary waste.

Each passenger left a footprint of 35.77 tons of carbon dioxide, enough to drive an average car 160,000 kilometers (100,000 miles).

"Flying virtually empty planes is an obscene waste of fuel. Through no fault of their own, each passenger's carbon footprint for this flight is about 45 times what it would have been if the plane had been full," Friends of the Earth's transport campaigner Richard Dyer said.

Because of a mechanical malfunction, AA flight 90 was 14 hours late leaving Chicago's O'Hare airport on February 8. Though most passengers made other arrangements to London, five lucky passengers unable to be rebooked made the 6,400 kilometer (4,000 mile) flight in business class, with two crew members per passenger.

American Airlines said it chose to continue with the flight because of the full load of passengers waiting at London's Heathrow airport to return to the United States.

"With such a small passenger load we did consider whether we could cancel the flight and re-accommodate the five remaining passengers on other flights," says American Airlines' European spokesperson Anneliese Morris.

"However, this would have left a plane load of west-bound passengers stranded in London Heathrow who were due to fly to the U.S. on the same aircraft."

Morris was quick to point out that despite the staggeringly low passenger count, the flight did carry a full cargo load.

Don't Miss

"We sought alternative flights for the west-bound passengers but heavy loads out of London meant that this was not possible. The only option was to operate the flight," Morris said.

"This put the aircraft in London Heathrow for the following day, enabling us to operate a full schedule and avoid further inconvenience to our passengers and cargo customers."

Environmental groups such as Friends of the Earth say that international governments should hold the aviation industry accountable for the amount of CO2 they produce each year, and point to instances like this to show that airlines should pay a fuel tax to rein them in.

"Governments must stop granting the aviation industry the unfair privileges that allow this to happen by taxing aviation fuel and including emissions from aviation in international agreements to tackle climate change," Dyer said.

But despite these accusations, Kieran Daly, air transport intelligence editor for Flight International magazine, said the amount passengers carried was irrelevant.

"Airlines are still a business. The cargo had to be flown and perhaps some of it was time-sensitive," Daly said.

"It's just not practical for an airline to tell its customers that it won't fly until it has a full passenger load. Customers won't be happy and the airline will quickly be out of business."E-mail to a friend